[Biological difficulties of a heavy chains disease diagnosis]. / Difficultés biologiques d'un diagnostic de maladie des chaînes lourdes.

Heavy chain diseases are rare gammopathies characterized by the production of a truncated heavy chain monoclonal immunoglobulin without associated light chain. These hemopathies, which are frequently associated with immunological or hematological disorders, are clinically closer to lymphomas than to myelomas. The case that we report illustrates the difficulty to characterize a heavy chain gammopathy discovered in an elderly woman admitted in the department of internal medicine for alteration of general condition.